CHOLESTEROL METABOLISM AND THE RISK OF HAIR LOSS
Cholesterol is used to make steroid hormones such as testosterone and vitamin D, as well as other products essential for cell survival. High levels of cholesterol have been found in populations with low testosterone and low vitamin D. Research shows a direct correlation between zinc levels and cholesterol levels . Pharmacological doses of between 35 mg and 50 mg of elemental zinc have been shown to be effective in lowering cholesterol but lower doses of 15 mg (the RDA for zinc) have no noticeable effect .
Supplementation with increases cholesterol conversion to vitamin D and testosterone via membrane-bound transcription factor peptidase site 2. This metalloprotease is essential for the uptake and metabolism of cholesterol within the cell.
A study conducted on 827 Italian factory workers in 1990 showed men with no hair loss had an average cholesterol level of 5.369 mmol/L, men with receding hairlines had an average cholesterol level of 5.387 mol/L and men with more severe hair loss had an average cholesterol level of 5.521 mol/L.
The central finding of another study , was the excess of cholesterol within the hair follicle niche can trigger an innate immune response that leads to the induction of Toll-like receptor and Interferon gamma gene expression. This leads to the activation and recruitment of T cells and macrophages that surround the hair follicles and initiates an inflammatory response resulting in the hairless lesions seen in alopecia areata.
Hair loss associated with abnormal cholesterol metabolism is also seen in women with low, normal or high levels of cholesterol. It appears the ratio of high density lipoproteins compared to low density lipoproteins is the factor that affects hair growth.